Bleach is not my first line of defense for water purification, but I can conceive a situation where it might be the only option. What I can't find is a definitive answer as to the proper dosage. Doug recommends six drops per gallon--so you know that has to be in the ballpark, but others, (including Fema) recommend 16 drops per gallon (one drop per cup) and others recommend up to 32 drops per gallon for "dirty" water. Does anyone know at what point the bleach could actually become poisonous--doing more harm than good? On the other end, does anyone know the minimum effective dosage(with some certainty that the water is properly purified)? It is surprising that there is such a wide range of suggested dosage regarding a process that has been around forever. Come on you chemistry guys....give us a break--and a clue! <br><br>take care,<br><br>Robb<br><br>If not now, when? If not us, who?